Eye registration and astigmatism alignment control systems and method

• US 20040143244A1
• Filed: 12/11/2003
• Published: 07/22/2004
• Est. Priority Date: 04/19/2000
• Status: Active Grant

• Current Assignee: Alcon Incorporated
• Original Assignee: Alcon RefractiveHorizons, LLC (Novartis Ag)
• Inventors: Campin, John Alfred, Gray, Gary Paul, Shen, Qiping
• Granted Patent: US 6,929,638 B2
• Time in Patent Office: Days
• US Class Current: 606/5
• CPC Class Codes: A61B 3/15 with means for aligning, spacing or blocking spurious reflection ; with means for relaxing
• CPC Class Codes: A61F 2009/00846 Eyetracking
• CPC Class Codes: A61F 2009/00872 Cornea
• CPC Class Codes: A61F 2009/0088 based on wavefront
• CPC Class Codes: A61F 9/00804 Refractive treatments

Abstract

An orientation system and method for corrective eye surgery includes a camera for performing a first image mapping of a patient'"'"'s eye using a predetermined eye feature and software for processing the first image map to determine an edge location of the feature. A second image mapping of the eye is performed with the patient in a different position. The second image map is processed to locate the predetermined eye feature. Correlation of the mappings is used to calculate an orientational change of the eye between the two positions. This procedure may also be performed at different times during surgery to permit “real-time” data on orientational changes undergone by the eye to be collected. In both cases the data are used to calculate an adjustment to be applied to a corrective prescription for application by the surgical procedure.

Claims

1. A method for orienting a corrective prescription for eye surgery comprising the steps of:

processing a first image map of an eye of a patient at a first time during the surgery to produce a first edge image of the eye in two dimensions;

processing a second image map of the patient eye at a second time during the surgery to produce a second edge image of the eye in two dimensions;

selecting two identifiable features from one of the first and the second image maps;

correlating a location of the two features in the first and the second edge images; and

calculating from the correlated locations an orientational change to be applied to a previously determined corrective prescription for a correction profile to be achieved on the eye during the surgery.

2. The method recited in claim 1, wherein the first and the second image maps comprise a first and a second video image captured with one of a charge-coupled-device camera, a scanning laser ophthalmoscope, and a retinal nerve fiber layer analyzer.

3. The method recited in claim 1, wherein the selected eye features comprise portions of at least one blood vessel in a sclera of the eye.

4. The method recited in claim 1, wherein the first and the second image map processing steps comprise filtering the first and the second image map, respectively, to reduce noise.

5. The method recited in claim 4, wherein the filtering steps comprise applying a Gauss filter to the first and the second image map and forming, from the first and the second filtered image maps, a first and a second filtered intensity profile.

6. The method recited in claim 5, wherein the first and the second image map processing steps further comprise applying a threshold to the first and the second filtered intensity profiles to produce a first and a second thresholded image.

7. The method recited in claim 6, wherein the first and the second image map processing steps further comprise applying a thin function to the first and the second thresholded image to form the first and the second edge images.

8. The method recited in claim 4, wherein the first and the second filtered intensity profile forming steps comprise:

applying the Gauss filter to the first and the second intensity profiles at a first angle to form a first and a third modified intensity profile;

applying the Gauss filter to the first and the second intensity profiles at a second angle substantially perpendicular to the first angle to form a second and a fourth modified intensity profile;

averaging the first and the second modified intensity profiles to form the first filtered intensity profile; and

averaging the third and the fourth modified intensity profiles to form the second filtered intensity profile.

9. The method recited in claim 1, wherein the surgical procedure comprises achieving a desired corneal profile using an excimer laser, and the orientational change calculating step comprises reorienting a coordinate system of the laser to compensate for eye movement between the first and the second time.

10. The method recited in claim 1, wherein the processing, selecting, correlating, and calculating steps are performed at predetermined intervals throughout the surgery, in order to detect orientational changes on a substantially continual basis and permit substantially “

real-time”

application of the orientational change to the correction profile.

11. A software package for orienting a corrective prescription for eye surgery comprising:

a code segment for processing a first image map of an eye of a patient at a first time during the surgery to produce a first edge image of the eye in two dimensions;

a code segment for processing a second image map of the patient eye at a second time during the surgery to produce a second edge image of the eye in two dimensions;

a code segment for correlating a location of two selected identifiable features from one of the first and the second image maps between the first and the second edge images; and

a code segment for calculating from the correlated locations an orientational change to be applied to a previously determined corrective prescription for a correction profile to be achieved on the eye during the surgery.

12. The software package recited in claim 11, wherein the first and the second image map processing code segments comprise code segments for filtering the first and the second image map, respectively, to reduce noise.

13. The software package recited in claim 12, wherein the filtering code segment comprises a code segment for applying a Gauss filter to the first and the second image map and for forming, from the first and the second filtered image maps, a first and a second filtered intensity profile.

14. The software package recited in claim 13, wherein the first and the second image map processing code segments further comprise code segments for applying a threshold to the first and the second filtered intensity profiles to produce a first and a second thresholded image.

15. The software package recited in claim 14, wherein the first and the second image map processing code segments further comprise code segments for applying a thin function to the first and the second thresholded image to form the first and the second edge images.

16. The software package recited in claim 13, wherein the first and the second filtered intensity profile forming code segment comprises:

a code segment for applying the Gauss filter to the first and the second intensity profiles at a first angle to form a first and a third modified intensity profile;

a code segment applying the Gauss filter to the first and the second intensity profiles at a second angle substantially perpendicular to the first angle to form a second and a fourth modified intensity profile;

a code segment averaging the first and the second modified intensity profiles to form the first filtered intensity profile; and

a code segment averaging the third and the fourth modified intensity profiles to form the second filtered intensity profile.

17. The software package recited in claim 11, wherein the surgical procedure comprises achieving a desired corneal profile using an excimer laser, and the orientational change calculating code segment comprises a code segment for reorienting a coordinate system of the laser to compensate for eye movement between the first and the second time.

18. The software package recited in claim 11, wherein the processing, correlating, and calculating code segments are performed at predetermined intervals throughout the surgery, in order to detect orientational changes on a substantially continual basis and permit substantially “

real-time”

application of the orientational change to the correction profile.

19. A system for orienting a corrective prescription for eye surgery comprising:

means for processing a first image map of an eye of a patient at a first time during the surgery to produce a first edge image of the eye in two dimensions;

means for processing a second image map of the patient eye at a second time during the surgery to produce a second edge image of the eye in two dimensions;

means for selecting two identifiable features from one of the first and the second image maps;

means for correlating a location of the two features in the first and the second edge images; and

means for calculating from the correlated locations an orientational change to be applied to a previously determined corrective prescription for a correction profile to be achieved on the eye during the surgery.

20. The system recited in claim 19, further comprising means for controlling the processing, selecting, correlating, and calculating means to be performed at predetermined intervals throughout the surgery, in order to detect orientational changes on a substantially continual basis and permit substantially “

real-time”

application of the orientational change to the correction profile.

21. A method for orienting a corrective prescription for eye surgery comprising the steps of:

processing a first image map of an eye of a patient at a first time during the surgery to produce a first edge image of the eye in two dimensions;

processing a second image map of the patient eye at a second time during the surgery to produce a second edge image of the eye in two dimensions;

selecting two identifiable features from one of the first and the second image maps;

correlating a location of the two features in the first and the second edge images; and

calculating from the correlated locations an orientational change to be applied to a previously determined corrective prescription for a correction profile to be achieved on the eye during the surgery;

wherein the processing, selecting, correlating, and calculating steps are performed at predetermined intervals throughout the surgery, in order to detect orientational changes on a substantially continual basis and permit substantially “

real-time”

application of the orientational change to the correction profile.

22. A software package for orienting a corrective prescription for eye surgery comprising:

a code segment for processing a first image map of an eye of a patient at a first time during the surgery to produce a first edge image of the eye in two dimensions;

a code segment for processing a second image map of the patient eye at a second time during the surgery to produce a second edge image of the eye in two dimensions;

a code segment for correlating a location of two selected identifiable features from one of the first and the second image maps between the first and the second edge images; and

a code segment for calculating from the correlated locations an orientational change to be applied to a previously determined corrective prescription for a correction profile to be achieved on the eye during the surgery;

wherein the processing, correlating, and calculating code segments are performed at predetermined intervals throughout the surgery, in order to detect orientational changes on a substantially continual basis and permit substantially “

real-time”

application of the orientational change to the correction profile.

23. A system for orienting a corrective prescription for eye surgery comprising:

means for processing a first image map of an eye of a patient at a first time during the surgery to produce a first edge image of the eye in two dimensions;

means for processing a second image map of the patient eye at a second time during the surgery to produce a second edge image of the eye in two dimensions;

means for selecting two identifiable features from one of the first and the second image maps;

means for correlating a location of the two features in the first and the second edge images;

means for calculating from the correlated locations an orientational change to be applied to a previously determined corrective prescription for a correction profile to be achieved on the eye during the surgery; and

means for controlling the processing, selecting, correlating, and calculating means to be performed at predetermined intervals throughout the surgery, in order to detect orientational changes on a substantially continual basis and permit substantially “

real-time”

application of the orientational change to the correction profile.